The present invention relates to an apparatus for extracting an injection-molded product from a mold, and particularly to an injection-molded product extracting apparatus for extracting from a mold an injection-molded openable/closable shutter used on a cartridge case for a disk-like recording medium.
Recently, disk-like recording media such as magnetic disks, optical disks, etc., have often been used in view of their simplicity of handling, high data storage capacity relative to volume, and the like. An example is a 3.5-inch micro-floppy diskette as shown in FIG. 4.
This micro-floppy disk 1 rotatably accommodates a magnetic disk 5 between upper and lower rectangular half-shells 2 and 3 formed of ABS resin or the like through injection molding. The magnetic disk 5 is a flexible magnetic recording medium in which a magnetic layer is formed uniformly on the surface of a disk-like macromolecular film base. A ring-like center plate 4 is fixedly attached to a circular opening formed at the center of the magnetic disk.
An opening 7 is formed at the center portion of the lower half-shell 3 of the diskette 1 so that a motor shaft can engage a substantially square opening 6 formed at the center portion of the center plate 4. Magnetic head insertion openings 8 are formed in the upper and lower half-shells 2 and 3 in the front portion of the micro-floppy diskette 1 so that a magnetic head can write information signals on and read such signals from the magnetic disk 5.
A sliding shutter 9 for opening/closing the magnetic head insertion openings 8 is provided on the micro-floppy diskette 1 in order to prevent dust or the like from entering through the magnetic head insertion openings 8 and adhering to the magnetic disk 5.
Conventionally, the shutter 9 has been formed by bending a metal plate such as a thin stainless steel plate or the like in a U-shape. The shutter includes a projection in the vicinity of the base portion of the shutter 9, which is guided within a guide groove provided along the outer front side edge of the lower half-shell 3 so that the shutter 9 is slidable in the direction to open/close the magnetic head insertion openings 8.
That is, the shutter 9 slides in a slide region 11 which includes the circumferential edges of the magnetic head insertion openings 8 and lies over one side of the micro-floppy disk 1. Opening portions 10 corresponding to the magnetic head insertion openings 8 are formed in the shutter 9 to expose the magnetic disk 5 while in use, while the magnetic head insertion openings 8 are closed by and the magnetic disk 5 is covered with the shutter 9 when the diskette is not in use.
Recently, there has been proposed a resin shutter, which can be produced easily and inexpensively by injection molding with synthetic resin, in place of a shutter formed of a metal plate material. Crystalline resin having a self-lubricating property such as polyacetal resin or the like, which has a sufficiently small sliding friction as to produce no resin dust while in use, is generally used to mold such a resin shutter. In the case of molding with crystalline resin, particularly in the case of molding a shutter by use of a thin mold portion into which resin is injected, it is necessary to ensure fluidity in the mold while injecting the resin by employing a high mold temperature (usually about 70.degree. to 90.degree. C.) to allow crystal growth to occur during the cooling time. As a result, the temperature of the molded product can reach 80.degree. to 100.degree. C. when it is extracted from the mold.
In order to extract such an injection-molded product and move it to the next stage of the manufacturing process, a chucking device, such as disclosed in Japanese Utility Model Unexamined Publications Nos. Sho-57-4310 and Sho-59-129517, has been used in which a pair of chuck members, which are opened/closed by a hydraulic cylinder, grasp a molded product from its opposite sides so as to sandwich the molded product between the chucking surfaces of the chuck members.
However, since a molded product in the form of a shutter not only has a high temperature coming out of the mold but also is very thin (in a range of 0.2 to 0.5 mm), if such a chucking device is used, the shutter can be easily deformed by the chucking force when the shutter is extracted from the mold.
Further, when an extremely thin shutter having a U-shaped section is sandwiched from its sides between the chucking surfaces as mentioned above, as shown in FIG. 5, often the molded product 9 is chucked in a slanted state such that only one outer surface portion of the molded product 9 contacts one chuck surface 51, the shutter is subjected to bending deformation, for example, in the connecting portion thereof, making it impossible to ensure accurate grasping and resulting in problems such as failure in carrying the shutter to the next stage.
Particularly because an elastic material 52 is generally provided on each chucking surface, right and left corner portions b of a back surface 9a of the molded product 9 are pressed into the chuck surfaces to form concave portions 53 in the elastic materials 52. Although these concave portions 53 actually contribute to holding the molded product 9 accurately, the portions immediately under the corner portions b are pushed inside the shutter by the chucking surfaces when the corner portions b are pressed into the chucking surfaces, so that there is a danger that the angles of the corner portions b can be changed to cause a serious defect in the shutter.
Further, as shown in FIG. 6, it may occur that the concave portions 53 do not immediately recover their original shapes after the molded product 9 is released from the chuck. Such a state results in problems such as deformation due to chucking so that grasping the molded product 9 cannot be performed accurately or the product is held in an inclined state.
To remedy the above problems, although it might be considered that the chucking force could be made small enough to avoid problems such as deformation due to chucking, the adjustment thereof has been very difficult since the accuracy of holding the shutter 9 is lowered if the chucking force is made small.
Another conventional apparatus for extracting a shutter from a mold operates by applying suction to the back surface of the shutter with a suction device to thereby improve the attitude of the extraction operation. However, in this apparatus, because the back surface (the plate surface connecting the front plate portion to the back plate portion) of the shutter is quite narrow (about 3.6 mm), the back surface must be very accurately positioned on the suction device in order to obtain a sufficient suction force. Therefore, in such a conventional apparatus, as shown in FIG. 7, an ejection pin 14 is provided to eject the shutter 9 from the mold a predetermined distance so as to make both sides of the shutter 9 contact a guide provided with an inclined guide surface 65, and only then reaching a suction device 63, to thereby guide the shutter 9 to the appropriate position.
However, the guide 64 for positioning the molded product can exert a relatively high force on the shutter 9. Also, the ejection pin 61 can be broken by the guide 64 in the case where the guide 64 is shifted a large amount due to the high temperature of the shutter 9 when the back surface portion of the shutter is inserted into the inclined guide surface 65.